4.1.1 Heat is added to 2 lbs of water in a piston-cylinder that starts off at 300 psi and an volume of 2.5 ft. If the pressure remains constant and the final temperature is 500F. What is the change in entropy? Ans: 0.474 Btu/R 4.1.2 Initially 2 kg of water at 100kPa that is a saturated liquid-vapor mix of water is in a well-insulated rigid tank with one-quarters of the mass is in the vapor phase. A heater in the tank is now activated and kept on until all the liquid in the tank is vaporized. What is the entropy change of the steam during this process? Ans: 8.10 kJ/K 4.1.3 5 L of saturated liquid water is in a piston-cylinder that is well insulated at 150 kPa. 2,200 kJ is added to water by an electric heater inside the. What is the entropy change of the water during this process? Ans: 5.72 kJ/K